The philanthropist and his family will leave their plush family home before Christmas and Mr Mellon's message to others as fortunate as himself is to "make sacrifices when the chips are down".

He said: "I've spent the last 10 years providing houses for the poor, so I know that size is not important when it comes to a home."

Mr Mellon, who has been recognised internationally for his work building homes in South Africa under the Niall Mellon Township Trust, said he was also undertaking the move out of an awareness of the image he is portraying in the current economic climate.

"I've been in the spotlight building houses for the poor and because of that I'm particularly conscious of the image I'm putting out there living in a house on five acres in Mount Merrion.

"In my own case, when I could afford to buy a big house I enjoyed living in it but things have changed. If I wanted to, I could probably hang on to it.

"But I feel in the current climate -- with so many people hurting -- that if Ireland has to have a chance of staying united in fighting this recession, it's important for all people in society to be seen to take some of the pain and make some sacrifices."

Speaking about the recent transferral of his property assets into Nama, Mr Mellon, who also put his 242-acre Kilkenny estate on the market recently, said: "Nama has not asked me to but my wife and I have recently put our country estate up for sale.

"We intend to move out of our Dublin home this side of Christmas with a view to renting it out and letting that pay for the mortgage.

"If this house can be developed and property value can be added, that will generate more money for Nama, then I'm happy to move out and obtain every cent we can get to adjust our Nama debt.

"It's important to my wife and me to do everything we can to pay our bills."

Asked about how he felt about leaving the family home in the run-up to Christmas, he said: "I'm sad for about 10 seconds and then I'm happy for the rest of the day. I have a great wife and three healthy young children and that's the way I see it.

"I'd encourage anyone who is financially challenged to focus on what's really important when the chips are down."

Speaking about the Niall Mellon Township Trust, which has become a major supplier of subsidised housing in South Africa, Mr Mellon said he was confident that his house-building charity would weather the recession following cutbacks over the past two years.

"Every active business person has been affected in this recession. We're all financially challenged at the moment. But no matter what happens, I intend to steer the charity safely through the recession."

The charity has cut its Dublin-based staff from 34 to 13 and halved the combined annual salaries of its five most senior executives, which had previously amounted to €442,000.

Meanwhile, he recently met President Jacob Zuma of South Africa, who is said to be taking a keen interest in the annual building blitz.

Mr Mellon said: "He has volunteered to come and support the Irish next year to show his support for the project and demonstrate to the South African people that working hand in hand we can all play a role in alleviating the dreadful conditions that these people live in."

Despite the impact of Ireland's economic crisis, Mr Mellon said the charity had enlisted almost 750 volunteers this year, each of whom will have raised €4,000-€5,000 to take part in house building in South Africa.

The Dublin-based developer started in property and financial services while in his 20s with the Niall J Mellon Group. He has extensive property interests in both Ireland and Britain.

Among the more high-profile purchases made by his company, Knockrabo Developments, was the €50m purchase of the Bank of Ireland playing fields in Goatstown in 2003.

He has recently scaled back his plans for the site, which overlooks Dublin city.